OCT – Ocular Coherence Tomography
What - in essence this machine takes a specialized photograph of the back of your eye. It allows a series of small cross-sectional photographs of the retina to be collected. You will need to rest your chin on the chin-rest of the OCT machine and look straight ahead at a target. The operator then lines up the appropriate part of your eye with the camera. You need to keep your eyes still during the image capture as this takes a little longer than a standard photograph – about a 1 second.
Why – there are different types and many reasons why you may need an OCT and your doctor will explain which is relevant to you. Most commonly OCT is used to assess the central retina (light sensitive part of the eye - “the film in the camera”) in cross-section as it gives very detailed images of the retinal anatomy. The OCT can also be used to assess the layers of the retina around the optic nerve (the nerve that takes the images to your brain).
Preparation – usually no specific preparation is required BUT occasionally we may use eye-drops to dilated your pupils in order to improve the view of the back of your eye. These drops may blur your vision for about 4 hours and you should NOT DRIVE until the effects have worn off completely. It is best therefore not to drive to such appointments.
Risk - there is no risk associated with OCT imaging. It will neither hurt nor affect your sight – although your vision may be blurred for a few hours if eye-drops are required to dilate your pupil.
How long will it take – each OCT image takes only a second or so to acquire but the computer processing may take a several seconds. If a few OCT images are required the whole process may take 5 minutes. If your pupils are dilated you may have to wait 15-20 minutes before the images can be taken and there may also be a queue!